Possible Consequences of Cryptophasia

Whether the phenomenon of Cryptophasia exists or not, the fact is that there are some findings that show that twins suffer more often from language impairments than singletons. After Schüller, several studies have shown that numerous twins are delayed in their pronunciation, which is "averagely 6 months behind the norm and they have reduced vocabulary knowledge at school as well as problems with their articulation" (Crystal 247). Mahieu found out that at the age of 5 years, twins had 158 different words, which was the level of three-years-old singletons. Nevertheless, Crystal describes some positive characteristics, which expresses that twins are also ahead of siblings in some aspects, like the ability to speak to adults or to keep a conversation going.

Some researches by Bishop & Bishop (1998) came to the result that "parents of twins with language impairment were significantly more likely to report a previous use of 'twin language' between their children than parents of twins with typically developing language abilities, 50% vs. 11%" (Mahieu 18).

To look deeper into the speech disorders that some of the twins develop:
There are certain linguistic methods that are used when using Cryptophasia, I.J Wolf gives an explanation to these in his "The Aetiology of Idioglossia" (2013):

Omission and Reduction:

are characterized by the omission of sounds
and- syllables' from words, usually the difficult sounds and unaccented
syllables. For instance, /boom/ is said for broom; /g'ome/ for go
home; /pa-bu/ for pocket-book.

Reduplication:

consists in the repetition of simple syllables to form
words. For instance, /moo-moo/ is said for cow; /bow-bow/ for dog.
These particular words imitate the sound of the thing indicated.

Assimilation:

The child who says /poom/ for spoon demonstrates
assimilation combined with omission. Assimilation is the modification
of one sound by another related in position or physiology. Thus /s/ is
omitted from spoon, and /n/ is labialized to become /m/ to conform
to the labial sounds /oo/ and /p/.

Substitution:

The various sounds comprising the velar, labial and
palatal groups are related in their mode of articulation. To one
inexperienced in making these sounds substitutions are common. The
most frequently seen are: /d/ for /g/ (/do/ for go); /t/ for /k/ (tat for cat); /d/ or /t/
for /th/ (/dis/ for this; /tree/ for three); /f/ for /th/ (/free/ for three); /b/ for /v/ (/bery/ for very); and /w/ for /r/ (/wun/ for run).

Metathesis:

Another manifestation of dyslalia is metathesis, which
consists in the transposition of sounds or syllables in a word, or the
transposition of words in a sentence. An example of transposition of sounds
in a word is /hopsital/ for hospital.

Analogy:

Finally there is analogy which is the confusion of words
due to a similarity in form, meaning or syntax (enemy for anemone; learn
for teach; foots for feet), or the creation of new words or the application of
new meanings to words by analagous association. Thus /burneator/ for
radiator; /splinters/ for moustache.

Dodd and McEvoy mention that in the speech of multiple-birth preschool children, they used a lot of unusual phonological processes, i.e. systematic speech errors that do not usually occur during normal development.

Some examples of these methods for omission are that some twins tend to delete "all or many word initial consonants, whereas singletons normally delete quite often only the /h/ sound" (Dodd & McEvoy 276).

In my survey I also questioned twins about speech disabilities in their childhood. Ten out of twenty-two participants declared that they had some kind of speech impairment as a child, of which nine of them even had their own language. Ten of them also gave a description of what it exactly was:

Two participants had a speech delay and one of that pair had their own language.

Two had problems with stuttering.

Two were lisping.

One had a morphological problem and changed the letters of the words.

Four had a problem of substitution; two of them changed /dr/ and /tr/ to /kr/; one of them /m/ to /n/; and the other one /i-/ to /ü-/ in front of /-ch/.

One had "speech difficulties" and saw a speech therapist because of that.

One of the speech defects of two German identical twin-girls, can be seen underneath the text in a small video. The girls are five years old in that video and are using some substitution: In three cases, the girls use /kr/ instead of /dr/ or /tr/, namely in the words drei (three), where /drai/ becomes /krai/ or in the word "drann", which is colloquial for "it's your turn". This /dran/ becomes /kran/ again.

None of these findings provide evidence for the existence of a "twin
language" and in how far it is connected to speech impairment. However, it seems to show a tendency towards the fact that phonologically disordered twins share an autonomous language. The final results to that will be, however, found on the survey-results-page.